EP1988389B1 - Surveillance of a zone with determination of the amount of contamination of a transparent surface based on the image contrast - Google Patents
Surveillance of a zone with determination of the amount of contamination of a transparent surface based on the image contrast Download PDFInfo
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- EP1988389B1 EP1988389B1 EP07008994A EP07008994A EP1988389B1 EP 1988389 B1 EP1988389 B1 EP 1988389B1 EP 07008994 A EP07008994 A EP 07008994A EP 07008994 A EP07008994 A EP 07008994A EP 1988389 B1 EP1988389 B1 EP 1988389B1
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- Prior art keywords
- contrast
- accordance
- contamination
- image contrast
- boundary surface
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/94—Investigating contamination, e.g. dust
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16P—SAFETY DEVICES IN GENERAL; SAFETY DEVICES FOR PRESSES
- F16P3/00—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body
- F16P3/12—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine
- F16P3/14—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine the means being photocells or other devices sensitive without mechanical contact
- F16P3/142—Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine the means being photocells or other devices sensitive without mechanical contact using image capturing devices
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8806—Specially adapted optical and illumination features
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
- G01N21/958—Inspecting transparent materials or objects, e.g. windscreens
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/46—Indirect determination of position data
- G01S17/48—Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/88—Lidar systems specially adapted for specific applications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V8/00—Prospecting or detecting by optical means
- G01V8/10—Detecting, e.g. by using light barriers
- G01V8/12—Detecting, e.g. by using light barriers using one transmitter and one receiver
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V10/00—Arrangements for image or video recognition or understanding
- G06V10/10—Image acquisition
- G06V10/12—Details of acquisition arrangements; Constructional details thereof
- G06V10/14—Optical characteristics of the device performing the acquisition or on the illumination arrangements
- G06V10/145—Illumination specially adapted for pattern recognition, e.g. using gratings
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V10/00—Arrangements for image or video recognition or understanding
- G06V10/98—Detection or correction of errors, e.g. by rescanning the pattern or by human intervention; Evaluation of the quality of the acquired patterns
- G06V10/993—Evaluation of the quality of the acquired pattern
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8806—Specially adapted optical and illumination features
- G01N2021/8829—Shadow projection or structured background, e.g. for deflectometry
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
- G01N2021/8854—Grading and classifying of flaws
- G01N2021/8861—Determining coordinates of flaws
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
- G01N2021/9511—Optical elements other than lenses, e.g. mirrors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/497—Means for monitoring or calibrating
- G01S2007/4975—Means for monitoring or calibrating of sensor obstruction by, e.g. dirt- or ice-coating, e.g. by reflection measurement on front-screen
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V2201/00—Indexing scheme relating to image or video recognition or understanding
- G06V2201/06—Recognition of objects for industrial automation
Definitions
- the invention relates to a device and a method for monitoring a spatial region with determination of the degree of contamination from the image contrast according to the preamble of claim 1 or 12.
- Such protective devices may be building or property protection applications that detect unauthorized intrusions and are ultimately prevented by intervention by security personnel.
- Another field of application is safety technology, in which an automated protective device monitors a source of danger within the room area and can control this source of danger via a controller. Hedging can here be understood as the timely switching off of a dangerous machine, but also the triggering of an alarm or a protective device such as a screen. Examples of a source of danger include a press that approaches operators in an unauthorized manner, but also a robot that must be used to protect nearby personnel in a collaborative work environment.
- the camera of the protection device has an actual image sensor, which is usually a CCD or CMOS chip.
- This chip and an upstream optics are protected by a housing that can be provided with a windshield as splash and dust protection against the space area.
- This windscreen or the upstream optics can contaminate and thus the safe Prevent detection of objects in the room area. Therefore, it is necessary to detect such contamination in time to continue to ensure the safety of the sensor by a maintenance and cleaning
- a special approach to pollution detection is from the DE 10 2004 020 998 A1 known, in which the entrance optics of the camera is shifted forward on the windshield. This is to ensure that impurities on the windscreen are distributed fairly uniformly over the entire image via the optics. Local contamination of the windscreen thus no longer covers a part of the room area, but overall reduces the brightness of the recorded image. This brightness decrease can be detected dynamically or by comparison with a reference brightness with a clean windshield.
- the contrast of a reference image is recorded. In operation, an image contrast value of the recorded image is determined in each case and compared with the reference contrast.
- a method of securing a hazardous area in which light is projected onto a given background and that background is monitored with a camera. Shades of light can be detected by the camera, and from the position of shading by means of triangulation, the position of an intervention in the area dominated by the light can be deduced.
- the JP 58 209 640 A shows a rain sensor for a windshield wiper of a motor vehicle.
- a contrast drop is detected in existing wind drops at one point of the windshield.
- the EP 1 659 421 A2 discloses a sensor for monitoring the proximity of a motor vehicle.
- persons are detected by means of an infrared receiving device to prevent accidents on a convertible top to be closed by a convertible.
- a decrease in the intensity of the received signal from an infrared emitter is detected in a measurement on the basis of the reception intensity. If a contamination is detected, the intensity of the infrared emitter is increased for the actual operation.
- a device according to claim 1 and a method according to claim 11.
- a contrasting pattern By actively projecting a contrasting pattern into the spatial area, sufficient image contrast is secured completely independently of the scene under surveillance.
- this contrast pattern allows a high local contrast gradient from which the image contrast can be calculated not only as a global global value, but also as additional and allowed finer criteria.
- the device monitors the contamination of the complete beam path.
- the invention is thus based on the principle of inferring quality measures of the recorded image on the contamination of the transparent interface. It uses the image contrast as a measure, whereby this image contrast can be specified by the active illumination with a contrast pattern with all desired properties. In this way, the image contrast contains a great deal of information about the nature and degree of contamination, and this information can also be selected specifically by the contrast pattern.
- the evaluation unit is designed to detect an object intervention in the spatial area, and it is provided a control, which is designed for the protection of a source of danger in the spatial area at object intervention.
- a control which is designed for the protection of a source of danger in the spatial area at object intervention.
- the evaluation unit is designed to determine the image contrast as a function of the location and can thus locate a contamination on the interface.
- the actively projected contrast pattern can produce contrast gradients in the spatial domain with virtually any desired accuracy. If this information is evaluated by the evaluation unit, deviations or changes in the local image contrast can be detected with high accuracy and can be deduced from it precisely on the location of the contamination on the interface.
- the device thus not only knows how heavily the boundary surface is polluted, but can also indicate specifically at which point such contamination is present. This can be exploited in an advantageous development for issuing a warning depending on the location of the pollution or switching to a fault mode. Because some contamination of the interface may not be at the point where the safety-critical parts of the room area are recorded. The device can thus differentiate whether the contamination is in an unimportant location or whether it is necessary to clean the interface. Within safety engineering, fault mode always means securing the source of danger.
- the evaluation unit is designed to determine the reference image contrast at a clean interface.
- the device In addition to the dynamic change in image contrast, which can be monitored during operation, the device thus also knows a target value for the image contrast and can more easily and accurately evaluate whether the image contrast has dropped to an extent that requires cleaning.
- the reference image contrast thus reflects the natural blur of the device.
- the image sensor is preceded by an optical filter adapted to the contrast pattern.
- an optical filter adapted to the contrast pattern.
- the image sensor is preceded by an optic which is protected by the interface. Not all dirt can be removed by simple cleaning, but it can also scratch and other damage occur. Then it is much cheaper to preserve the delicate and valuable optics and only exchange the transparent interface.
- the evaluation unit is designed to determine the reference image contrast by utilizing a known basic contrast function of the optics and / or the interface. This is ultimately an alternative to compute the reference image contrast from the captured image and supports the accuracy of this reference image contrast determination from theoretically known values.
- the device preferably has a stereo camera or a distance-measuring camera, in particular according to the time of flight principle.
- a stereo camera or a distance-measuring camera in particular according to the time of flight principle.
- Such three-dimensional image sensors allow a particularly great flexibility in the establishment of protection zones that are considered dangerous, and a particularly accurate monitoring of the space area.
- the device has a distance-measuring camera according to the principle of active triangulation, wherein the contrast pattern is at the same time a complex triangulation pattern.
- the active triangulation is a special method for the determination of distance values, which in contrast to the stereo camera requires only one camera and, in contrast to a distance-measuring camera according to the time of flight principle, does not require high-precision electronics for the evaluation of the extremely short light propagation times.
- active triangulation only works with a complex contrast pattern, which contains the required information density, which is needed as the basis for the triangulation.
- one and the same contrast pattern can enable both the active triangulation and the contamination measurement according to the invention.
- the contrast illumination device is monochromatic. This not only makes the lighting, but also the evaluation less expensive, the accuracy of the contrast values is still maintained. Especially in cooperation with a matched to the monochromatic frequency range filter the image contrast can be determined very accurately.
- inventive method can be configured in a similar manner by further features and shows similar advantages. Such others Features are exemplary, but not exhaustive, described in the appended subclaims.
- FIG. 1 shows a first embodiment of the device 10 according to the invention for monitoring a spatial area.
- An image sensor 12 which is preceded by an optical system 14, is arranged protected in a housing 16.
- the image sensor 12 is capable of taking a pixel-resolved image of a spatial region 20 through a transparent interface 18.
- the image sensor 12 may be, for example, a line or matrix-shaped CCD or CMOS chip.
- the transparent interface 18 may be made of glass or a transparent plastic and is often designed as a windshield.
- the upstream optical system 14 is shown in simplified form as a simple converging lens, but here, alternatively, any refractive, reflective or diffractive optical system can also be made of several components, as they are known per se from camera lenses.
- the image sensor 12 is connected to an evaluation unit 22, which can read out and process the image data. This image data is then examined as to whether an event is detected in the space area 20 to which it is to respond. Such an event may be the unauthorized intervention of an object in the space area 20, a movement or entry of the space area 20 by operators or any other conceivable change reflected in the image data. One way to find such events is to compare the image taken during operation with a previously learned reference image.
- the evaluation unit 22 in turn is connected to a controller 24.
- This controller 24 is capable of responding to an event reported by the evaluation unit 22 by issuing an alarm, turning on a warning light, or monitoring a source of danger monitored by the apparatus 10 by shutting down a machine, retiring, closing a door, or the like Protective screen or the like is hedged.
- the evaluation unit 22 is also connected to a lighting 26 and can turn this on and off or to cause the selection of a particular type of lighting. Deviating from the illustration, evaluation unit 22, control 24 and illumination 26 can be provided in whole or in part also within housing 16 or also over known wired or wireless interfaces at a greater distance.
- the illumination 26 actively projects a contrast pattern into the spatial area 20 during operation FIG. 1 It is only possible to recognize a very schematic, simplified rectangular object 28 in the spatial region 20, on which the illumination 26 generates a dot pattern arranged in a matrix.
- This dot pattern is to be understood as an example only, any other pattern may be provided as long as it provides a sufficiently strong contrast varying over the space.
- These include stripe patterns, grid patterns, but in particular also complex irregular patterns, in which the structure of each sub-area can be closed to its position.
- the light source in the illumination 26 may serve a conventional bulb or halogen lamp, but is preferably a semiconductor light source such as a diode or a laser.
- the contrast pattern is produced, for example, by a corresponding mask or a targeted scanning by means of a narrowly limited light source.
- the light source can be monochromatic.
- the evaluation unit 22 determines the image contrast of the images taken by the image sensor. This image contrast is high and easy to determine due to the contrast pattern actively projected by the illumination 26.
- the evaluation unit 22 compares the respectively determined image contrast with either values previously determined during operation or with a reference contrast value which has been previously learned in with a known clean interface 18.
- a reference contrast value which represents the natural blur of the image sensor
- a known basic contrast function of the optics 14 and the interface 18 can be incorporated. This basic contrast function is thus theoretically determined from the properties of optics 14 and interface 18, thus already known in advance and can help to make the reference contrast value more accurate.
- the contrast pattern can have a high contrast gradient at any location due to its choice, it is not only possible to determine a global contrast value, but also a very finely resolved local function of the contrast, depending on the contrast pattern. From the local variation of this function it can then not only be concluded that the interface 18 is even polluted, but at the same time the location and the degree of contamination of each contaminant can be determined and evaluated.
- the device 10 is thus able to locally assess the contamination and to trigger an alarm or malfunction only if the contamination is in a critical area, so for example before the source of danger. On the other hand, there are impurities, especially in peripheral layers, which initially do not require maintenance. The device 10, if it assesses such contamination as uncritical, can continue to operate without any loss of reliability.
- the optical system 14 or the interface 18 may additionally have an optical filter adapted to the contrast pattern.
- an optical filter adapted to the contrast pattern.
- FIG. 1 only a simple camera is shown.
- a distance-resolving camera may also be provided which thus supplies three-dimensional image data.
- Such three-dimensional image data can be evaluated much more accurately because protection zones can be spatially and flexibly defined around sources of danger.
- the scene can also be easily evaluated dynamically in this way, because a shadowing of the source of danger does not necessarily mean that the shaded object is close to the source of danger. This can only be assessed by means of the distance.
- the speed of the intervening object can be much better evaluated from distances, and slow movement at a certain distance from a source of danger may still be uncritical, which would not be fast movement.
- the three-dimensional evaluation is thus much more reliable and rarely causes unnecessary false positives.
- One technique for obtaining a three-dimensional image is a stereo camera in which two or more cameras record the space area 20 from different perspectives and are closed to the distance from the location of corresponding objects in the pictures by disparity estimation.
- An alternative technique is a distance-measuring camera according to the principle of the light transit time, which actively illuminates the space region 20 and measures how long the light needs for the path from the illumination 26 via the object 28 to the image sensor 12. In this case, therefore, the illumination 26 has a double function for determining the light transit time on the one hand and for increasing the contrast in the spatial region 20 on the other hand.
- the contrast pattern projected by the illumination 26 is used to evaluate the position of structures within this contrast pattern by means of triangulation and to deduce the distance therefrom.
- Each structural feature of the contrast pattern, in the representation of FIG. 1 thus, each of the points forms a triangulation basis 30.
- the special structure of the complex contrast pattern also serves here twice on the one hand to increase the contrast image value and, on the other hand, to determine the distance.
- FIG. 2 a further embodiment of the invention is shown.
- like reference numerals designate the same features.
- the difference of this embodiment is that optic 14 and transparent interface 18 coincide.
- the interface 18 is thus at the same time the optics or at least part of the optics 14.
- another contrast pattern is illustrated to illustrate that this contrast pattern may have a different shape than that according to FIG. 1 , As already explained above, the contrast pattern is not limited to the two forms shown.
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Abstract
Description
Die Erfindung betrifft eine Vorrichtung und ein Verfahren zur Überwachung eines Raumbereichs mit Bestimmung des Verschmutzungsgrads aus dem Bildkontrast nach dem Oberbegriff von Anspruch 1 beziehungsweise 12.The invention relates to a device and a method for monitoring a spatial region with determination of the degree of contamination from the image contrast according to the preamble of
Zur Überwachung von Raumbereichen werden in zunehmendem Maße kamerabasierte Schutzeinrichtungen als Sensoren verwendet. Bei solchen Schutzeinrichtungen kann es sich um Anwendungen im Gebäude- oder Objektschutz handeln, bei dem ein unerlaubtes Eindringen bemerkt und letztlich meist durch Eingreifen von Sicherheitspersonal verhindert wird. Ein anderes Anwendungsfeld ist die Sicherheitstechnik, bei der eine automatisiert arbeitende Schutzeinrichtung eine Gefahrenquelle innerhalb des Raumbereichs überwacht und über eine Steuerung die Absicherung dieser Gefahrenquelle vornehmen kann. Unter Absichern kann hierbei das rechtzeitige Abschalten einer gefährlichen Maschine, aber auch das Auslösen eines Alarms oder einer Schutzvorrichtung wie beispielsweise eines Schirms verstanden werden. Beispiele für eine Gefahrenquelle sind eine Presse, der sich Bedienpersonal in unerlaubter Weise nähert, aber auch ein Roboter, vor dem in einem kooperativen Arbeitsumfeld das in der Nähe arbeitende Personal geschützt werden muss.For monitoring room areas, increasingly camera-based protection devices are used as sensors. Such protective devices may be building or property protection applications that detect unauthorized intrusions and are ultimately prevented by intervention by security personnel. Another field of application is safety technology, in which an automated protective device monitors a source of danger within the room area and can control this source of danger via a controller. Hedging can here be understood as the timely switching off of a dangerous machine, but also the triggering of an alarm or a protective device such as a screen. Examples of a source of danger include a press that approaches operators in an unauthorized manner, but also a robot that must be used to protect nearby personnel in a collaborative work environment.
Die Kamera der Schutzeinrichtung weist einen eigentlichen Bildsensor auf, der für gewöhnlich ein CCD- oder CMOS-Chip ist. Dieser Chip und eine vorgeschaltete Optik sind von einem Gehäuse geschützt, das mit einer Frontscheibe als Spritz- und Staubschutz gegenüber dem Raumbereich versehen sein kann. Diese Frontscheibe oder die vorgeschaltete Optik kann verunreinigen und damit die sichere Detektion von Objekten in dem Raumbereich verhindern. Daher ist es notwendig, eine solche Verschmutzung rechtzeitig zu erkennen, um durch eine Wartung und Reinigung die Sicherheit des Sensors weiterhin zu gewährleistenThe camera of the protection device has an actual image sensor, which is usually a CCD or CMOS chip. This chip and an upstream optics are protected by a housing that can be provided with a windshield as splash and dust protection against the space area. This windscreen or the upstream optics can contaminate and thus the safe Prevent detection of objects in the room area. Therefore, it is necessary to detect such contamination in time to continue to ensure the safety of the sensor by a maintenance and cleaning
Im Stand der Technik sind mehrere Ansätze bekannt, die Verschmutzungen zu detektieren. Nicht alle diese Ansätze sind auch von Kameras bekannt, sondern nur von anderen Sensoren, wie etwa einem Laserscanner. So ist beispielsweise bekannt, die Frontscheibe mit einem separaten Strahlengang zu durchstrahlen, um dabei den Empfangspegel mit einem bei sauberer Frontscheibe aufgenommenen Referenzempfangspegel zu vergleichen.In the prior art, several approaches are known to detect the contamination. Not all of these approaches are known by cameras, but only by other sensors, such as a laser scanner. For example, it is known to irradiate the windshield with a separate beam path in order to compare the reception level with a recorded with clean windscreen reference reception level.
Ein besonderer Ansatz zur Verschmutzungsdetektion ist aus der
Nach diesem Stand der Technik sind also Helligkeit oder Bildkontrast zwei mögliche Maße für die Verschmutzung der Frontscheibe. Nachteilig an dem Ansatz ist, dass die Vorverlagerung der Aperturblende zur Frontscheibe eine sehr ungewöhnliche Objektivausführung ist, die weder mit kostengünstigen, im Handel erhältlichen Bauteilen umgesetzt werden kann noch insgesamt ein für die Bildqualität optimales Objektiv darstellt. Weiterhin wird bei beiden Ausführungsformen nur ein globales Verschmutzungsmaß bestimmt, welches unklar lässt, wie die Verunreinigungen örtlich auf der Frontscheibe oder äußersten Fläche des Objektivs verteilt sind. Schließlich ist nicht sichergestellt, ob der überwachte Raumbereich überhaupt an sich einen hinreichenden Kontrast aufweist, der eine Detektion eines Abfalls dieses Kontrasts mit der in der Sicherheitstechnik notwendigen hohen Zuverlässigkeit erlaubt.According to this prior art, brightness or image contrast are two possible measures for the contamination of the windshield. A disadvantage of the approach is that the forward displacement of the aperture to the windshield is a very unusual lens design that can be implemented neither with inexpensive, commercially available components still represents an overall optimum for the image quality lens. Furthermore, in both embodiments only a global level of soiling is determined, which leaves unclear how the contaminants are distributed locally on the windshield or outermost surface of the lens. Finally, it is not ascertained whether the monitored area of space in itself has sufficient contrast per se, which allows a detection of a drop in this contrast with the high reliability required in safety technology.
Aus der
Die
Die
Es ist daher Aufgabe der Erfindung, eine Überwachungsvorrichtung der geschilderten Art anzugeben, deren Funktion nicht von Verschmutzungen beeinträchtigt wird.It is therefore an object of the invention to provide a monitoring device of the type described, whose function is not affected by contamination.
Diese Aufgabe wird erfindungsgemäß durch eine Vorrichtung gemäß Anspruch 1 und ein Verfahren gemäß Anspruch 11 gelöst. Indem ein Kontrastmuster aktiv in den Raumbereich projiziert wird, ist ein ausreichender Bildkontrast völlig unabhängig von der überwachten Szene gesichert. Dieses Kontrastmuster ermöglicht zugleich einen hohen lokalen Kontrastgradienten, aus dem der Bildkontrast nicht nur als ein pauschaler globaler Wert berechnet werden kann, sondern weitere und feinere Kriterien erlaubt. Gegenüber herkömmlichen Systemen, welche die transparente Grenzfläche mit einem eigenen Strahl durchleuchten, sind auch die Herstellungskosten und die Baugröße reduziert. Die erfindungsgemäße Vorrichtung überwacht die Verschmutzung des kompletten Strahlengangs.This object is achieved by a device according to claim 1 and a method according to claim 11. By actively projecting a contrasting pattern into the spatial area, sufficient image contrast is secured completely independently of the scene under surveillance. At the same time, this contrast pattern allows a high local contrast gradient from which the image contrast can be calculated not only as a global global value, but also as additional and allowed finer criteria. Compared to conventional systems, which illuminate the transparent interface with its own beam, the manufacturing cost and size are reduced. The device according to the invention monitors the contamination of the complete beam path.
Die Erfindung geht damit von dem Prinzip aus, von Qualitätsmaßen des aufgenommenen Bildes auf die Verschmutzung der transparenten Grenzfläche zu schließen. Sie nutzt den Bildkontrast als Maß, wobei dieser Bildkontrast durch die aktive Beleuchtung mit einem Kontrastmuster mit allen gewünschten Eigenschaften vorgegeben werden kann. Auf diese Weise enthält der Bildkontrast sehr viele Informationen über Art und Grad der Verschmutzung, wobei diese Informationen durch das Kontrastmuster auch gezielt gewählt werden können.The invention is thus based on the principle of inferring quality measures of the recorded image on the contamination of the transparent interface. It uses the image contrast as a measure, whereby this image contrast can be specified by the active illumination with a contrast pattern with all desired properties. In this way, the image contrast contains a great deal of information about the nature and degree of contamination, and this information can also be selected specifically by the contrast pattern.
Bevorzugt ist die Auswertungseinheit dafür ausgebildet, einen Objekteingriff in den Raumbereich zu erkennen, und es ist eine Steuerung vorgesehen, welche für die Absicherung einer Gefahrenquelle in dem Raumbereich bei Objekteingriff ausgebildet ist. Dies ist die Anwendung der Vorrichtung in der Sicherheitstechnik, bei der die Kontrolle über die Verschmutzung der Grenzfläche besonders wichtig ist, um die Zuverlässigkeit jederzeit zu gewährleisten.Preferably, the evaluation unit is designed to detect an object intervention in the spatial area, and it is provided a control, which is designed for the protection of a source of danger in the spatial area at object intervention. This is the application of the safety device, in which the control of the contamination of the interface is particularly important to ensure reliability at all times.
Erfindungsgemäß ist die Auswertungseinheit dafür ausgebildet, den Bildkontrast als Funktion des Ortes zu bestimmen und kann somit eine Verschmutzung auf der Grenzfläche lokalisieren. Das aktiv projizierte Kontrastmuster kann mit nahezu jeder gewünschten Genauigkeit Kontrastgradienten in dem Raumbereich erzeugen. Werden diese Informationen von der Auswertungseinheit ausgewertet, so können Abweichungen oder Veränderungen des lokalen Bildkontrasts mit hoher Genauigkeit erkannt und daraus genau auf den Ort der Verschmutzung auf der Grenzfläche geschlossen werden. Die Vorrichtung weiß somit nicht nur, wie stark die Grenzfläche verschmutzt ist, sondern kann auch gezielt angeben, an welcher Stelle eine solche Verschmutzung vorliegt. Dies kann in einer vorteilhaften Weiterbildung dafür ausgenutzt werden, abhängig vom Ort der Verschmutzung eine Warnung auszugeben oder in einen Fehlermodus zu schalten. Denn manche Verschmutzungen der Grenzfläche liegen möglicherweise überhaupt nicht an der Stelle, wo die sicherheitskritischen Teile des Raumbereichs aufgenommen werden. Die Vorrichtung kann auf diese Weise differenzieren, ob die Verschmutzung an einer unwichtigen Stelle liegt oder ob es notwendig ist, die Grenzfläche zu reinigen. Innerhalb der Sicherheitstechnik bedeutet Fehlermodus dabei immer gleichzeitig das Absichern der Gefahrenquelle.According to the invention, the evaluation unit is designed to determine the image contrast as a function of the location and can thus locate a contamination on the interface. The actively projected contrast pattern can produce contrast gradients in the spatial domain with virtually any desired accuracy. If this information is evaluated by the evaluation unit, deviations or changes in the local image contrast can be detected with high accuracy and can be deduced from it precisely on the location of the contamination on the interface. The device thus not only knows how heavily the boundary surface is polluted, but can also indicate specifically at which point such contamination is present. This can be exploited in an advantageous development for issuing a warning depending on the location of the pollution or switching to a fault mode. Because some contamination of the interface may not be at the point where the safety-critical parts of the room area are recorded. The device can thus differentiate whether the contamination is in an unimportant location or whether it is necessary to clean the interface. Within safety engineering, fault mode always means securing the source of danger.
In einer bevorzugten Ausführungsform ist die Auswertungseinheit dafür ausgebildet, den Referenzbildkontrast bei sauberer Grenzfläche zu bestimmen. Über die dynamische Veränderung des Bildkontrasts hinaus, die während des Betriebs überwacht werden kann, kennt die Vorrichtung auf diese Weise auch einen Sollwert für den Bildkontrast und kann daraus einfacher und genauer bewerten, ob der Bildkontrast in einem Maße abgefallen ist, das eine Reinigung erfordert. Der Referenzbildkontrast spiegelt somit die natürliche Unschärfe der Vorrichtung wieder.In a preferred embodiment, the evaluation unit is designed to determine the reference image contrast at a clean interface. In addition to the dynamic change in image contrast, which can be monitored during operation, the device thus also knows a target value for the image contrast and can more easily and accurately evaluate whether the image contrast has dropped to an extent that requires cleaning. The reference image contrast thus reflects the natural blur of the device.
Bevorzugt ist dem Bildsensor ein an das Kontrastmuster angepasster optischer Filter vorgeschaltet. Somit erreicht weniger Störlicht den Bildsensor, und die aufgenommenen Bilddaten reflektieren mit höherer Zuverlässigkeit relevante Eigenschaften des Raumbereichs und des Kontrastmusters. Folglich wird auch die Ermittlung des Bildkontrastwerts genauer.Preferably, the image sensor is preceded by an optical filter adapted to the contrast pattern. Thus, less stray light reaches the image sensor, and the recorded ones Image data reflect with higher reliability relevant properties of the spatial area and the contrast pattern. Consequently, the determination of the image contrast value becomes more accurate.
Bevorzugt ist dem Bildsensor eine Optik vorgeschaltet, die von der Grenzfläche geschützt ist. Nicht jede Verschmutzung kann durch einfache Reinigung beseitigt werden, sondern es können auch Kratzer und sonstige Beschädigungen auftreten. Dann ist es wesentlich kostengünstiger, die empfindliche und wertvolle Optik zu erhalten und nur die transparente Grenzfläche auszutauschen.Preferably, the image sensor is preceded by an optic which is protected by the interface. Not all dirt can be removed by simple cleaning, but it can also scratch and other damage occur. Then it is much cheaper to preserve the delicate and valuable optics and only exchange the transparent interface.
Vorteilhafterweise ist die Auswertungseinheit dafür ausgebildet, den Referenzbildkontrast unter Ausnutzung einer bekannten Basiskontrastfunktion der Optik und/oder der Grenzfläche zu bestimmen. Dies ist letztlich eine Alternative dazu, den Referenzbildkontrast aus dem aufgenommenen Bild zu berechnen, und unterstützt die Genauigkeit dieser Referenzbildkontrastbestimmung aus theoretisch bekannten Werten.Advantageously, the evaluation unit is designed to determine the reference image contrast by utilizing a known basic contrast function of the optics and / or the interface. This is ultimately an alternative to compute the reference image contrast from the captured image and supports the accuracy of this reference image contrast determination from theoretically known values.
Bevorzugt weist die Vorrichtung eine Stereokamera oder eine entfernungsmessende Kamera insbesondere nach dem Lichtlaufzeitprinzip auf. Solche dreidimensionalen Bildsensoren ermöglichen eine besonders große Flexibilität bei der Einrichtung von Schutzzonen, die als gefährlich gelten, und eine besonders genaue Überwachung des Raumbereichs.The device preferably has a stereo camera or a distance-measuring camera, in particular according to the time of flight principle. Such three-dimensional image sensors allow a particularly great flexibility in the establishment of protection zones that are considered dangerous, and a particularly accurate monitoring of the space area.
Als alternativer dreidimensionaler Sensor weist die Vorrichtung eine nach dem Prinzip der aktiven Triangulation entfernungsmessende Kamera auf, wobei das Kontrastmuster zugleich ein komplexes Triangulationsmuster ist. Die aktive Triangulation ist ein besonderes Verfahren zur Bestimmung von Entfernungswerten, die im Gegensatz zur Stereokamera mit nur einer Kamera auskommt und im Gegensatz zu einer entfernungsmessenden Kamera nach dem Lichtlaufzeitprinzip keine hochgenaue Elektronik zur Auswertung der extrem kurzen Lichtlaufzeiten benötigt. Aktive Triangulation funktioniert aber nur mit einem komplexen Kontrastmuster, welches die erforderliche Informationsdichte enthält, die als Basis für die Triangulation benötigt wird. Gemäß dieser besonderen Ausführungsform kann ein und dasselbe Kontrastmuster sowohl die aktive Triangulation wie auch die erfindungsgemäße Verschmutzungsmessung ermöglichen.As an alternative three-dimensional sensor, the device has a distance-measuring camera according to the principle of active triangulation, wherein the contrast pattern is at the same time a complex triangulation pattern. The active triangulation is a special method for the determination of distance values, which in contrast to the stereo camera requires only one camera and, in contrast to a distance-measuring camera according to the time of flight principle, does not require high-precision electronics for the evaluation of the extremely short light propagation times. However, active triangulation only works with a complex contrast pattern, which contains the required information density, which is needed as the basis for the triangulation. According to this particular embodiment, one and the same contrast pattern can enable both the active triangulation and the contamination measurement according to the invention.
In einer weiteren Ausführungsform ist die Kontrastbeleuchtungseinrichtung monochromatisch. Das macht nicht nur die Beleuchtung, sondern auch die Auswertung weniger aufwändig, die Genauigkeit der Kontrastwerte bleibt dennoch erhalten. Besonders in Zusammenwirkung mit einem auf den monochromatischen Frequenzbereich abgestimmten Filter kann der Bildkontrast sehr genau bestimmt werden.In a further embodiment, the contrast illumination device is monochromatic. This not only makes the lighting, but also the evaluation less expensive, the accuracy of the contrast values is still maintained. Especially in cooperation with a matched to the monochromatic frequency range filter the image contrast can be determined very accurately.
Das erfindungsgemäße Verfahren kann auf ähnliche Weise durch weitere Merkmale ausgestaltet werden und zeigt dabei ähnliche Vorteile. Derartige weitere Merkmale sind beispielhaft, aber nicht abschließend, in den sich anschließenden Unteransprüchen beschrieben.The inventive method can be configured in a similar manner by further features and shows similar advantages. Such others Features are exemplary, but not exhaustive, described in the appended subclaims.
Die Erfindung wird nachstehend auch hinsichtlich weiterer Vorteile und Merkmale unter Bezugnahme auf die beigefügte Zeichnung anhand von Ausführungsbeispielen erläutert. Die Figuren der Zeichnung zeigen in:
- Fig. 1
- eine schematische Übersichtsdarstellung der erfindungsgemäßen Vorrichtung mit einem aktiv projizierten Kontrastmuster gemäß einer ersten Ausführungsform; und
- Fig. 2
- eine Darstellung gemäß
Figur 1 einer zweiten Ausführungsform der Erfindung, bei der die transparente Grenzfläche zugleich einen Teil der Abbildungsoptik der Vorrichtung darstellt.
- Fig. 1
- a schematic overview of the device according to the invention with an actively projected contrast pattern according to a first embodiment; and
- Fig. 2
- a representation according to
FIG. 1 a second embodiment of the invention, in which the transparent interface at the same time forms part of the imaging optics of the device.
Der Bildsensor 12 ist mit einer Auswertungseinheit 22 verbunden, welche die Bilddaten auslesen und verarbeiten kann. Diese Bilddaten werden daraufhin untersucht, ob in dem Raumbereich 20 ein Ereignis erkannt wird, auf das zu reagieren ist. Ein solches Ereignis kann der unerlaubte Eingriff eines Objekts in den Raumbereich 20, eine Bewegung oder ein Betreten des Raumbereichs 20 durch Bedienpersonal oder jede sonst denkbare, in den Bilddaten reflektierte Veränderung sein. Eine Möglichkeit, solche Ereignisse aufzufinden, ist der Vergleich des im Betrieb aufgenommenen Bildes mit einem zuvor eingelernten Referenzbild.The
Die Auswertungseinheit 22 wiederum ist mit einer Steuerung 24 verbunden. Diese Steuerung 24 ist in der Lage, auf ein von der Auswertungseinheit 22 gemeldetes Ereignis zu reagieren, indem ein Alarm ausgegeben, ein Warnlicht eingeschaltet oder eine von der Vorrichtung 10 überwachte Gefahrenquelle durch Abschalten einer Maschine, Versetzen in einen Ruhestand, Schließen einer Tür oder eines Schutzschirms oder dergleichen abgesichert wird.The
Die Auswertungseinheit 22 ist außerdem mit einer Beleuchtung 26 verbunden und kann diese ein- und ausschalten oder zur Auswahl einer bestimmten Beleuchtungsart veranlassen. Abweichend von der Darstellung können Auswertungseinheit 22, Steuerung 24 und Beleuchtung 26 insgesamt oder teilweise auch innerhalb des Gehäuses 16 oder auch über bekannte drahtgebundene oder drahtlose Schnittstellen in größerer Entfernung vorgesehen sein.The
Die Beleuchtung 26 projiziert im Betrieb aktiv ein Kontrastmuster in den Raumbereich 20. In
Als Lichtquelle in der Beleuchtung 26 kann eine gewöhnliche Glühbirne oder Halogenleuchte dienen, bevorzugt ist aber eine Halbleiterlichtquelle wie eine Diode oder ein Laser. Das Kontrastmuster entsteht dabei beispielsweise durch eine entsprechende Maske oder ein gezieltes Abscannen mittels einer eng begrenzten Lichtquelle. Um den apparativen Aufwand zu begrenzen und die Auswertung zu erleichtern, kann die Lichtquelle monochromatisch sein.As the light source in the
Um nun erfindungsgemäß die Verschmutzung der transparenten Grenzfläche 18 zu überwachen, bestimmt die Auswertungseinheit 22 den Bildkontrast der von dem Bildsensor aufgenommenen Bilder. Dieser Bildkontrast ist aufgrund des von der Beleuchtung 26 aktiv projizierten Kontrastmusters hoch und gut zu bestimmen. Die Auswertungseinheit 22 vergleicht den jeweils bestimmten Bildkontrast entweder mit zuvor während des Betriebs ermittelten Werten oder mit einem Referenzkontrastwert, der vorab bei bekannt sauberer Grenzfläche 18 eingelernt worden ist. In diesen Referenzkontrastwert, der die natürliche Unschärfe des Bildsensors darstellt, kann auch eine bekannte Basiskontrastfunktion der Optik 14 beziehungsweise der Grenzfläche 18 einfließen. Diese Basiskontrastfunktion ist also theoretisch aus Eigenschaften von Optik 14 und Grenzfläche 18 ermittelt, somit schon vorab bekannt und kann helfen, den Referenzkontrastwert genauer zu machen.In order to monitor the contamination of the
Da das Kontrastmuster an jedem Ort aufgrund seiner Wahl einen hohen Kontrastgradienten aufweisen kann, ist es nicht nur möglich, einen globalen Kontrastwert zu ermitteln, sondern eine je nach Kontrastmuster auch sehr fein aufgelöste örtliche Funktion des Kontrasts. Aus der lokalen Variation dieser Funktion kann dann nicht nur geschlossen werden, dass die Grenzfläche 18 überhaupt verschmutzt ist, sondern zugleich auch der Ort und der Verschmutzungsgrad einer jeden Verunreinigung bestimmt und bewertet werden. Die Vorrichtung 10 ist auf diese Weise in der Lage, die Verunreinigung örtlich zu bewerten und nur dann einen Alarm oder eine Fehlfunktion auszulösen, wenn die Verunreinigung in einem kritischen Bereich, also beispielsweise vor der Gefahrenquelle liegt. Andererseits gibt es Verunreinigungen gerade in peripheren Lagen, die zunächst keine Wartung notwendig machen. Die Vorrichtung 10 kann, wenn sie eine solche Verschmutzung als unkritisch bewertet, ohne jeglichen Verlust an Zuverlässigkeit weiterbetrieben werden.Since the contrast pattern can have a high contrast gradient at any location due to its choice, it is not only possible to determine a global contrast value, but also a very finely resolved local function of the contrast, depending on the contrast pattern. From the local variation of this function it can then not only be concluded that the
Die Optik 14 oder die Grenzfläche 18 können zusätzlich einen an das Kontrastmuster angepassten optischen Filter aufweisen. Somit werden von vorneherein nur solche optischen Frequenzen durchgelassen, die dem Kontrastmuster entsprechen, was besonders einfach ist, wenn dieses monochromatisch ist. Auf diese Weise kann der Einfluss durch Licht von Fremdstörern zurückgedrängt werden, und die Auswertung sowie die Bestimmung des Bildkontrasts wird genauer.The
In der
Eine Technik, ein dreidimensionales Bild zu erhalten, ist eine Stereokamera, bei der zwei oder mehrere Kameras den Raumbereich 20 aus verschiedener Perspektive aufnehmen und aus der Lage von korrespondierenden Objekten in den Bildern mittels einer Disparitätsschätzung auf die Entfernung geschlossen wird. Eine Alternativetechnik ist eine entfernungsmessende Kamera nach dem Prinzip der Lichtlaufzeit, welche den Raumbereich 20 aktiv beleuchtet und misst, wie lange das Licht für den Weg von der Beleuchtung 26 über das Objekt 28 zum Bildsensor 12 braucht. Hierbei hat also die Beleuchtung 26 eine Doppelfunktion zum Ermitteln der Lichtlaufzeit einerseits und zur Erhöhung des Kontrastes im Raumbereich 20 andererseits.One technique for obtaining a three-dimensional image is a stereo camera in which two or more cameras record the
Eine weitere Möglichkeit, ein entfernungsauflösendes Bild zu erhalten, ist die aktive Triangulation. Hierbei wird das von der Beleuchtung 26 projizierte Kontrastmuster dafür ausgenutzt, die Lage von Strukturen innerhalb dieses Kontrastmusters mittels einer Triangulation zu bewerten und daraus auf die Entfernung zu schließen. Jedes strukturelle Merkmal des Kontrastmusters, in der Darstellung der
In
Claims (15)
- An apparatus (10) for monitoring a spatial zone (20) having at least one image sensor (12) which has a transparent boundary surface (18), in particular a front screen or a front lens, as well as having an evaluation unit (22) which is designed to determine a reference image contrast at a known degree of contamination as well as to determine the image contrast of images taken by the image sensor (12) and to determine a degree of contamination of the boundary surface (18) from the image contrast and to include the reference image contrast in the determination of the degree of contamination by comparison with the image contrast,
characterized in that
a contrast illumination device (26) is provided which is designed to illuminate the spatial zone (20) with a contrast pattern; and in that the evaluation unit (22) is designed to determine the image contrast as a function of the location and thus to localize contamination on the boundary surface (18). - An apparatus (10) in accordance with claim 1,
wherein the evaluation unit (22) is designed to recognize an object intrusion into the spatial zone (20); and wherein a control (24) is provided which is designed for the securing of a source of danger in the spatial zone (20) on intrusion of an object. - An apparatus (10) in accordance with claim 1 or claim 2,
wherein the evaluation unit (22) is designed to output a warning or to switch into an error mode in dependence on the location of the contamination. - An apparatus (10) in accordance with any one of the preceding claims,
wherein the evaluation unit (22) is designed to determine the reference image contrast with a clean boundary surface (18). - An apparatus (10) in accordance with any one of the preceding claims,
wherein an optical filter (14, 18) adapted to the contrast pattern is connected before the image sensor (12). - An apparatus (10) in accordance with any one of the preceding claims,
wherein an optical system (14) is connected before the image sensor (12) and is protected by the boundary surface (18). - An apparatus (10) in accordance with claim 7,
wherein the evaluation unit (22) is designed to determine the reference image contrast while utilizing a known basic contrast function of the optical system (14) and/or of the boundary surface (18). - An apparatus (10) in accordance with any one of the preceding claims,
which has a stereo camera or a distance-measuring camera, in particular in accordance with the time of flight of light principle. - An apparatus (10) in accordance with any one of the preceding claims,
which has a distance-measuring camera in accordance with the principle of active triangulation, wherein the contrast pattern is simultaneously a complex triangulation pattern. - An apparatus (10) in accordance with any one of the preceding claims,
wherein the contrast illumination device is monochromatic. - A method of monitoring a spatial zone (20) having at least one image sensor (13) protected by a transparent boundary surface (18), in particular a front screen or a front lens, wherein a reference image contrast is determined at a known degree of contamination and the image contrast of images taken by the image sensor (12) in operation is determined and a degree of contamination of the boundary surface (18) is determined from the image contrast while including a comparison between the image contrast of the images taken in operation and of the reference image contrast,
characterized in that
the spatial zone (20) is actively illuminated by a contrast pattern; and in that the image contrast is determined as a function of the location and thus contamination on the boundary surface (18) is localized. - A method in accordance with claim 11,
wherein the spatial zone (20) is monitored for an object intrusion and a source of danger in the spatial zone (20) is secured on an object intrusion. - A method in accordance with claim 11 or claim 12,
wherein a warning is output or the source of danger is secured in dependence on the location of the contamination. - A method in accordance with any one of the claims 11 to 13, wherein the reference image contrast is determined with a clean boundary surface or while utilizing a known basic contrast function of an optical system (14 and/or of the boundary surface (18).
- A method in accordance with any one of the claims 11 to 14, wherein the monitoring utilizes the principle of active triangulation; and wherein the contrast pattern is simultaneously a complex triangulation pattern.
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AT07008994T ATE517333T1 (en) | 2007-05-04 | 2007-05-04 | MONITORING A SPACE AREA WITH DETERMINATION OF THE LEVEL OF POLLUTION OF A TRANSPARENT BORDER USING THE IMAGE CONTRAST |
EP07008994A EP1988389B1 (en) | 2007-05-04 | 2007-05-04 | Surveillance of a zone with determination of the amount of contamination of a transparent surface based on the image contrast |
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DE102008061035C5 (en) | 2008-12-08 | 2013-09-05 | Sick Ag | Method and optical sensor for detecting objects |
EP2469300B1 (en) * | 2011-04-18 | 2012-08-22 | Sick Ag | 3D camera and method for three dimensional surveillance of a surveillance area |
JP5902049B2 (en) | 2012-06-27 | 2016-04-13 | クラリオン株式会社 | Lens cloudiness diagnostic device |
DE102012015282B4 (en) * | 2012-08-01 | 2023-03-16 | Application Solutions (Electronics and Vision) Ltd. | Method for detecting a covered state of an image capturing device of a motor vehicle, camera system and motor vehicle |
DE102017222618A1 (en) | 2017-12-13 | 2019-06-13 | Robert Bosch Gmbh | LiDAR system with integrated contamination detection and corresponding procedure for the detection of soiling |
EP3715907B1 (en) | 2019-03-27 | 2024-02-28 | Infineon Technologies AG | Methods and apparatuses for compensating light reflections from a cover of a time-of-flight camera |
CN113781424B (en) * | 2021-09-03 | 2024-02-27 | 苏州凌云光工业智能技术有限公司 | Surface defect detection method, device and equipment |
CN115359431B (en) * | 2022-10-21 | 2023-02-28 | 山东省生态环境监测中心 | Atmospheric environment pollution source pollution degree evaluation method and system |
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DE10033608A1 (en) * | 2000-07-11 | 2002-02-07 | Pilz Gmbh & Co | Securing an area around a machine tool to prevent entrance of personnel and possible injury using artificial light target, the image of which can be compared to a reference value and used to switch off the machine |
DE102004020998A1 (en) * | 2004-04-19 | 2005-11-03 | Pilz Gmbh & Co. Kg | Device for monitoring a room area, in particular for securing a danger zone of an automated system |
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